Ketotifen: A Role in the Treatment of Idiopathic Anaphylaxis

Abstract

Idiopathic anaphylaxis is a life-threatening disease characterized by acute and recurrent episodes of urticaria, angioedema, airway compromise, gastrointestinal symptoms and shock. It is diagnosed when a patient has signs and symptoms of anaphylaxis without any apparent triggers. The treatment consists of anti-histamines and oral steroids. However, long term prednisone therapy has a variety of known debilitating side effects. Ketotifen is an oral anti- allergic drug which also inhibits the release of mast cell and basophil mediators. It has been shown to be effective for treating chronic urticaria and idiopathic anaphylaxis. We describe 6 patients with corticosteroid dependent idiopathic anaphylaxis who were successfully treated with ketotifen. Detailed history, physical examination and extensive laboratory evaluation failed to indicate any specific trigger of their anaphylaxis. The duration of symptoms prior to treatment ranges from one month to 13 years. All patients had angioedema, urticaria or both. Some patients had various concomitant medical conditions but none of them was shown to be casually related with their anaphylactic episodes. Some of them were on long term prednisone treatment. All patients were placed on 2-4 mg ketotifen orally twice daily. Among the 6 patients, one had an episode of recurrence requiring increased dose of ketotifen. Five of the 6 patients were able to come off prednisone without recurrence of symptoms. Our clinical experience suggests that ketotifen is effective in inducing remission of corticosteroid dependent idiopathic anaphylaxis. More studies are needed to determine the role of Ketotifen in the treatment of idiopathic anaphylaxis.